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United States Patent |
5,541,383
|
Renner
,   et al.
|
July 30, 1996
|
Arc welded joint between a carrier and a component rigidly connected to
it
Abstract
Arc welded joint between a carrier and a metal component with a continuous
recess into which a stud-like weld-in part is introduced, wherein the
weld-in part which consists of a shank and an enlarged head is pressed
into the recess and into the pool of melt formed on the carrier so that
the pool of melt adjacent to the wall of the recess embraces the outer rim
of the head, the pool of melt directly connecting the component to the
adjacent carrier. The rim of the head may be designed as a radial melting
edge which is located completely within the recess of the component and
has a substantially blade-like cross section.
Inventors:
|
Renner; Wolf (Giessen, DE);
Mauer; Dieter (Lollar, DE)
|
Assignee:
|
Emhart Inc. (Newark, DE)
|
Appl. No.:
|
385510 |
Filed:
|
February 8, 1995 |
Foreign Application Priority Data
| Aug 02, 1991[DE] | 41 25 748.0 |
| Aug 20, 1991[DE] | 41 27 527.6 |
| Sep 20, 1991[DE] | 41 31 405.0 |
| Apr 14, 1992[DE] | 42 12 513.8 |
Current U.S. Class: |
219/99 |
Intern'l Class: |
B23K 009/20 |
Field of Search: |
219/98,99,127
403/271
|
References Cited
U.S. Patent Documents
2635167 | Apr., 1953 | Nelson | 219/99.
|
2922542 | Jan., 1960 | Barr | 219/99.
|
3035158 | May., 1962 | Copleston et al. | 219/127.
|
3182172 | May., 1965 | Dash | 219/98.
|
3774009 | Nov., 1973 | Hodges | 219/98.
|
Foreign Patent Documents |
3149513 | Jun., 1983 | DE | 219/99.
|
53-81444 | Jul., 1978 | JP | 219/98.
|
60-162581 | Aug., 1985 | JP | 219/99.
|
603784 | Jun., 1948 | GB | 219/98.
|
1075969 | Jul., 1967 | GB | 219/99.
|
Primary Examiner: Shaw; Clifford C.
Attorney, Agent or Firm: Murphy; E. D.
Parent Case Text
This application is a division of application Ser. No. 08/272,956, filed
Jul. 11, 1994, now U.S. Pat. No. 5,393,164, which is a continuation of
earlier filed application Ser. No. 07,923,393, filed Jul. 31, 1992, now
abandoned.
Claims
We claim:
1. A method of connecting metal members via a welded joint comprising the
steps of
providing an assembly comprising a sheet metal carrier; a sheet metal
component overlying said carrier, said component having a bore
therethrough; and a plug comprising a head, said head being located
partially within said bore and having a first surface facing said carrier
and a second surface facing away from said carrier;
establishing a welding arc within said bore;
creating a pool of melt made up of material from said carrier, said
component and said plug;
plunging said plug into said pool to force material from said pool to flow
out of said bore and over said second surface of said head; and
allowing said pool to solidify.
2. A method as claimed in claim 1 wherein said plunging step compresses
melted material from said pool against the circumference of said bore to
produce fusion with said component.
3. A method as claimed in claim 1 wherein said first surface of said head
protrudes toward said carrier at its center to provide a centrally located
gap for initiation of said arc.
4. A method as claimed in claim 3 wherein said first surface is tapered
away from said centrally located gap to provide for propagation of said
arc toward the circumference of said bore.
5. A method as claimed in claim 3 wherein said head is provided with a rim
between said first and second surfaces; said rim is positioned to face the
upper edge of said bore in said component; and said arc is extended to
encompass said rim and said upper edge of said bore; said pool including
material from the upper and lower edges of said bore in said component.
6. A method as claimed in claim 5 wherein said rim is tapered to a sharp
edge to allow rapid melting thereof in any region where the gap between
said rim and said bore is reduced relative to other regions.
Description
BACKGROUND OF THE INVENTION
The invention relates to an arc welded joint between a carrier as one
electrode and a metal component with a continuous recess into which a
stud-like weld-in part is introduced as the other electrode, which is
rigidly connected to the carrier and the component by arc welding.
A welded joint of this type is known from DE-AS 1 565 563. With this welded
joint a shell-type metal sheet is arranged on a steel carrier, for which
purpose the shell-type metal sheet is pressed against the steel carrier by
means of a steel plate welded on the steel carrier. The weld between the
steel plate and the steel carrier is produced by means of a stud which
passes through the steel plate and is also guided through a hole in the
shell-type metal sheet. The stud is welded to the steel carrier by arc
butt welding, a continuous weld being produced between the steel carrier,
the stud and the steel plate. This weld is not impaired by the shell-type
metal sheet because its hole is sufficiently large for its rims still to
be at a considerable distance from the weld. Furthermore, the shell-type
metal sheet should not be included in the weld because it is usually
provided with a corrosion-preventing coating, for example zinc coating or
plastics material. These coatings, in particular zinc, would evaporate
during the welding process. The vapour penetrating the weld impairs the
alloy forming the welding pool. Furthermore, the shell-type metal sheet
complicates the welding process as it necessarily produces a distance
between the steel carrier and the steel plate which then has to be bridged
over by the pool of melt and the weld produced from it.
One object of the present invention is to design the bond produced by the
weld between a carrier, a metal component and a stud-like weld-in part
particularly thoroughly and therefore with comparatively high strength.
BRIEF DESCRIPTION OF THE INVENTION
According to the present invention, we provide an arc-welded joint between
a carrier as one electrode and a metal component with a continuous recess
into which a stud-like weld-in part is introduced as the other electrode
which is rigidly connected to the carrier and the component by arc welding
wherein the weld-in part consists of a shank and a head which is enlarged
in relation to the shank diameter via a step, penetrates into the recess
in the component resting on the carrier and, owing to the formation of a
pool of melt on the carrier, can be pressed into this pool of melt such
that the pool of melt adjacent to the wall of the recess embraces the
outer rim of the head and the step, the pool of melt directly connecting
the component, at least in the region of the edge of the wall of the
recess facing the carrier, directly to the adjacent carrier.
Owing to the construction of the weld-in part from a shank having a head
which is enlarged in relation to it and owing to the use of the pool of
melt pressed up over the outer rim of the head, the space between the end
face of the head and the component is reliably and completely filled by
the pool of melt which penetrates the carrier, the wall of the recess and
the weld-in part and rises adjacently to the wall of the recess, on the
one hand, and passes over the outer rim of the head and the step on the
other hand. This produces mainly an intensive weld in the region of the
edge of the wall of the recess facing the carrier and the carrier resting
on the component and--resembling a riveted joint--the surrounding of the
head in the step region so that the component resting directly on the
carrier is securely welded at the critical point of the edge of the wall
of the recess facing the carrier and, on the other hand, the weld-in part
is continuously drawn to the carrier by the pool of melt passing over the
step, the weld-in part pressing the wall parts of the recess connected to
it via the pool of melt against the carrier.
Preferably, the weld-in part consists of a shank and a head which is
enlarged relative to the shank diameter by a step, protrudes with its
outer rim slightly beyond the component and penetrates into the recess in
the component resting on the carrier with a projection such that, owing to
the formation of an arc extending to the edge, remote from the carrier, of
the wall of the recess, the projection can be pressed into the pool of
melt to cover the entire wall of the recess including its two edges as
well as the carrier and the head to its outer rim.
Owing to the construction of the weld-in part from a shank having a head
which is enlarged relative thereto and which protrudes with its outer rim
slightly beyond the component, the effect is achieved that the electric
arc travels from the end face of the head toward this outer rim until it
reaches the edge, remote from the carrier, of the wall of the recess and
incorporates this edge in the pool of melt which is being formed. The pool
of melt is therefore supplied to a considerable extent out of the
projection or step of the weld-in part penetrating into the recess of the
component so that a pool of melt is formed which covers the entire wall of
the recess including its two edges as well as the carrier and the head
virtually to its outer rim, the step behind the outer rim of the head
preventing the electric arc from travelling beyond the outer rim. Owing to
the slight protrusion of the outer rim beyond the respective edge of the
recess, this edge is reliably included in the pool of melt, resulting in
reliable welding which covers the entire wall of the recess including its
two edges as well as the carrier and the head up to its outer rim.
The head is preferably constructed such that it is substantially lenticular
in design round its outer rim and the projection projects substantially
cylindrically round the depth of the recess. The projection therefore
substantially fills the recess and therefore makes an adequate quantity of
material available for the formation of a uniform pool of melt on melting.
It is a further object of the invention to design the weld-in part so that
automatic centering of the weld-in part in the recess in the metal
component takes place when weld-in part and metal component are brought
together.
In another preferred embodiment of the invention, this can be achieved in
that the rim of the head is designed as a radial melting rim which is
located completely inside the recess in the component and has a
substantially blade-like cross section.
When this weld-in part and the component are brought together, the
blade-like rim of the head is received completely within the recess of the
component, ensuring that the weld-in part does not rest somehow laterally
next to or partially next to the recess of the component. Complete
introduction of the rim of the head of the weld-in part into the recess
therefore guarantees centering of weld-in part and recess so that co-axial
centering is not necessary. Even when the rim of the weld-in part does in
fact rest on the internal face of the recess, arcing initially occurs at
the point of contact when the arc is switched on and a radial distance is
formed between the head and the recess as the rim melts there so that the
arc between the head and the component is finally distributed over the
entire rim of the weld-in part and the entire rim is caused to melt. This
produces a distance between the head and the recess which is such that the
arc passes over the curvature and concentrates thereon. This distribution
of the arc over the entire rim of the head of the weld-in part causes
melting which extends over the entire rim, owing to the blade-like cross
section of the rim, and therefore results in a pool of melt in the region
of the bottom of the recess into which the weld-in part can then finally
be pressed, as described in the main patent, for welding the component to
the carrier.
The blade-like cross section in the region of the rim of the head ensures
rapid melting of this rim and therefore the direct formation of the pool
of melt. The blade-like cross section is still maintained in principle
even if the melting rim is formed as a thin disc projecting radially from
the head, as the thin disc projecting radially from the head, as the thin
disc can be melted quickly and the pool of melt consequently forms
correspondingly quickly.
It is yet another object of the invention to design the weld-in part so as
to provide substantially uniform heat distribution over the weld-in part
during the welding process. According to the present invention, this may
be achieved by providing the weld-in part with a bore which extends
through the shank into the head and is such that the wall thickness of the
shank in the bore region corresponds approximately to the thickness of the
end wall of the bore of the welding zone in the welded state.
The bore extending into the head results, on the one hand, in heat
dissipation which is considerably reduced in relation to a solid weld-in
part during the welding process, which has a desirable influence on the
energy requirement for the welding process, and, on the other hand, in
heat distribution over all parts to be welded which extends substantially
uniformly over the parts so that extreme heating at specific points of the
parts to be welded is avoided. The heat capacity of the weld-in part which
is reduced owing to the bore extending into the head also leads to a
substantially uniform cooling rate over the entire welding region during
the cooling process so that the weld is kept free from internal stresses.
It is expedient to adapt the diameter of the bore to the periphery of
expanding jaws of a setting tool constructed as a welding tool so that the
weld-in part can be conveyed in a desirable manner, i.e. it is taken from
a magazine, transferred to the welding point and positioned thereon. The
gripping of the weld-in part via the wall of the bore allows considerable
expansion forces and consequently good contact so that virtually no
harmful resistances to transmission can build up at the contact point. The
gripping of the weld-in part from the interior allows particularly
accurate positioning as virtually no displacement thereof can occur when
the weld-in part is gripped by the expanding jaws.
The following state of the art is mentioned for the sake of completeness:
A process for fastening plates on aluminium sheets is described in DE-OS 3
149 513, in which the plates are provided, in the sense of the
above-mentioned metal component, with a hole to which an aluminium stud is
inserted as an electrode for an arc welding process. The stud is to be
connected to the metal sheet (in the sense of the foregoing carrier) only
but its end face as the plate to be fastened on the the metal sheet is
provided, on the side facing the metal sheet, with an indentation which
receives spurting metal during the welding process and therefore prevents
this metal from passing between plate and metal sheet. The plate is
fastened on the metal sheet by the aluminium stud which is mushroom-shaped
and presses onto the plate with its head which is constructed slightly
conically on its underside. The resultant tensile forces are then absorbed
only by the welding on the end face of the stud as a comprehensive weld
which also includes the plate is not intended with the process. The idea
of including the wall of the recess in the weld, which emerges from the
above described invention, and, in particular, the passing of the melt
bath over the step is therefore completely lacking in the design produced
by the known process.
With a process known from DE-PS 18 11 820 for the welding of studs onto a
carrier with interposed zinc-coated sheet metal employing th stud welding
process, the hole required in the sheet metal for guiding through the stud
and welding it to the carrier is provided by burning through the sheet
metal during the burning of the arc required for welding. This burning of
the arc while the sheet metal is burning through is adjusted such that
zinc vapours formed in the process are removed before initiation of the
actual welding current for connecting stud and carrier.
Reference is finally made to GB-PS 1 000 577 which disclosed a weld stud
consisting of a shank and a head which is enlarged in relation to it and
of which the end face forms the weld point. The end face can be conical or
curved in design. In the case of the design with an enlarged head, the
curvature passes via a sharp edge in a cone which tapers in the direction
toward the shank and which the cylindrical shank then adjoins. Nothing
else about the use of this weld stud can be inferred from this document.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be better understood, a number of
embodiments will be described in greater detail by way of example with
reference to the accompanying drawings, in which:
FIG. 1 shows the assembly of carrier, metal component and weld-in part in
the position of contact between carrier and weld-in part;
FIG. 2 shows the arrangement of FIG. 1 with the weld-in part lifted from
the carrier and with the arc formed;
FIG. 3 shows the arrangement of FIG. 1 with a solidified pool of melt;
FIG. 4 is a perspective view of two metal sheets which are welded to one
another using the embodiment of FIG. 1 and of the weld-in part projecting
from the upper metal sheet;
FIG. 5 shows an alternative weld-in part in a side view;
FIG. 6 shows the weld-in part of FIG. 5 gripped by a setting tool and
brought into the welding position;
FIG. 7 shows the weld-in part of FIG. 5 welded to a carrier and a metal
component;
FIG. 8 shows the assembly of carrier, metal component and a modified
weld-in part in the position of contact between carrier and weld-in part;
FIG. 9 shows the arrangement of FIG. 8 after electric arc welding with a
solidified pool of melt;
FIG. 10 shows a fourth variant of the weld-in part, inserted into a metal
component, with lateral contact of the rim of the weld-in part on the
internal face of the recess;
FIG. 11 is a plan view of the weld-in part of FIG. 10;
FIG. 12 shows the weld-in part of FIG. 10 with a firing arc;
FIG. 13 shows a variation of the design of the rim of the weld-in part of
FIG. 10 with a sharply issuing edge, and
FIG. 14 shows a further variation of the design of the rim of the weld-in
part of FIG. 10.
DETAILED DESCRIPTION OF EMBODIMENTS AND DRAWINGS
Referring to the embodiment illustrated by FIGS. 1, 2, 3 and 4, FIG. 1
shows the carrier 1 which is constructed from a piece of sheet metal and
onto which the metal component 2, which can be formed, for example, from a
sheet metal strip, is placed directly. The metal component 2 is provided
with the recess 3 which is a round bore in the simplest case into which
the weld-in part 4 is inserted. The weld-in part 4 is held by a welding
tool of which only the holding jaws 5 and 6 are indicated schematically
here. As the arc welding process used in this connection is a known
process, reference is made to known welding tools which are provided with
corresponding clamping jaws.
The weld-in part 4 has the shank 7 which is preferably cylindrical in
design. The shank 7 passes via the cone 8 into the rim 9 which si also
preferably constructed cylindrically. The spherically shaped camber 10
adjoins the rim 9. Cone 8, rim 9 and camber 10 therefore form a head 11
whose external diameter provided by the rim 9 is greater than the diameter
of the shank 7. The diameter of the head 11 is smaller than the opening of
the recess 3 so that the head 11 is held in the recess 3 relative to the
component 2 substantially without contact. The cone 8 forms the
above-mentioned step which can also be constructed as a radial face. A
bore 16 which can serve to receive any parts is provided in the shank 7.
The weld-in part 4 is pressed against the carrier 1 by the holding jaws 5
and 6. The carrier 1 forms one electrode and the weld-in part 4 the other
electrode for a voltage which serves to ignite a welding arc and is
applied in a known manner to the welding tool (not shown) and the carrier
1. The welding arc is then struck in a known manner by lifting the weld-in
part 4 from the carrier 1.
FIG. 2 shows the same arrangement with the struck arc, which is indicated
here by the dotted lines 12 radiating from the camber 10. Owing to the
contact in the centre of the camber 10 shown in FIG. 1, the welding arc is
initially ignited at this point which, after the weld-in part 4 has been
lifted from the carrier 1, forms the shortest path for the arc so that the
arc causes the carrier to melt in the region of the foremost part of the
camber 10 relative to the carrier 1. Owing to the subsequent increase in
the welding current, following in a known manner, the arc also encompasses
the outer regions of the camber 10 and finally passes into the region of
the upper edge 13 of the recess 3, producing a pool of melt which covers
the entire surface of the carrier 1 opposite the camber 10, the camber 10
and the well of the recess 3. A flat cone can also be provided instead of
the camber 10.
As the weld-in part 4 is again brought toward the carrier 1, the weld-in
part 4 plunges with its camber 10 in the pool of melt and, in so doing,
displaces the melt which, as shown in FIG. 3, rises between the rim 9 and
the wall of the recess 3 and finally passes over the edge 9 and the cone
8, forming the bead 14. In the process of melting and forming the pool of
melt, the ledge 15 of the wall of the recess 3 resting on the carrier 1 is
mainly included so that the pool of melt is also formed at this point
which is particularly important for the rigid connection, the pool of melt
penetrating into the carrier 1, the component 2 and the weld-in part 4 so
as to produce, between the parts, an intimate connection which is
particularly reinforced by the bead 14 which, in a manner of speaking,
presses the head 11 of the weld-in part 4 against the component as with
riveting.
FIG. 4 shows the weld between the carrier 1 and the component 2 in a
perspective view. The weld-in part 4 projects from the component 2 round
which the bead 14 formed by the raised pool of melt extends and
additionally embraces the weld-in part 4.
The carrier and the metal component may be metal sheets or the like. It is
also possible to construct the metal component as a thicker constructional
element which then merely has to be provided with the above-described
recess into which the head of the weld-in part has to penetrate. The
described arc weld is also suitable, in particular, for the welding of
aluminium parts with which welding is known to be difficult. In
particular, aluminium sheets can only be connected to one another with
difficulty by the known spot welding process as the oxide skin present on
the aluminium sheets has to be broken through. Apart from this, it should
be noted during spot welding that the electrodes placed on the metal
sheets are contaminated relatively rapidly and therefore have to be
continually cleaned. With the arc welded joint according to the invention,
on the other hand, new electrodes are constantly provided, namely in the
form of the carrier on the one hand and in the form of the weld-in part on
the other hand.
Referring to the embodiment illustrated by FIGS. 8 and 9, FIG. 8 shows the
carrier 1 which is formed from a piece of sheet metal and onto which there
is directly placed the metal component 2 which can be formed, for example,
from a sheet metal strip. The metal component 2 is provided with the
recess 3, a round bore into which the weld-in part 4 is inserted in the
simplest case. The weld-in part 4 is held in a known manner by any welding
tool.
The weld-in part 4 has the shank 7 which is preferably cylindrical in
construction. The shank 7 passes into the lenticular head 11 which extends
via the conical step 8 to its outer rim 9. The outer rim 9 protrudes
slightly beyond the component 2, i.e. the rim 9 has a slightly greater
diameter than the recess 3 in the case of cylindrical design. The
lenticular head 11 is then followed by the step 17 which penetrates into
the recess 3 and finally passes into the cone 10 resting with its tip 18
on the carrier 1. The weld-in part 4 and the carrier 1 form the two
electrodes for the electric arc which is being formed, an electric contact
between the carrier 1 and the metal component 2 obviously also existing
owing to the resting of the metal component 2 on the carrier 1.
The step 17 has a somewhat smaller diameter than the recess 3 so that,
after retraction of the weld-in part 4 from the carrier 1, an electric arc
is formed between the cone 10 and the carrier 1, the electric arc
expanding with a corresponding increase in the welding current over the
total projection 3 and the head 11 to the outer rim 9 thereof. The
electric arc causes the edge 13 to melt in the region between the outer
rim 9 and the edge 13 of the component 2. The pool of melt being formed
between the cone 10 and the carrier 1 is also supplied by material from
the step 17 so that the pressing of the weld-in part 4 into the pool of
melt results in welding to beyond the edge 13 which is partially melted in
the process, forming an intimate rigid joint between the weld-in part 4,
the component 2 and the carrier 1.
FIG. 9 shows the welded-in weld-in part 4. As shown, a weld zone 19 which
extends to and includes the outer rim 9 is formed. The molten outer rim 9
is located substantially at the level of the surface, remote from the
carrier 1, of the component 2, the weld-in zone 19 being shown as a slight
elevation at the surface of the component.
Referring now to the embodiment illustrated in FIGS. 10, 11, 12 and 13,
FIG. 10 shows the carrier 1 which is formed from a piece of sheet metal
and onto which the metal component 2, which may be formed, for example, by
a strip of sheet metal, is placed directly. The metal component 2 is
provided with the recess 3, in the simplest case a round bore into which
the weld-in part 4 is inserted. As described above, the weld-in part 4 is
held by a suitable welding tool and is introduced into the recess 3.
The weld-in part 4 has the stem 7 which is preferably cylindrical in
design. The head 11 is formed from the cone 8, the thin disc 9A and the
camber 10 adjoins the stem 7. In this case, the thin disc 9A projects
radially outwardly in the form of a blade or disc from the head 11. The
diameter of the thin disc 9A is smaller than the diameter of the recess 3
so that the thin disc 9A rests completely within the recess 3 when weld-in
part 4 and component 2 are brought together. The height of the camber 10
and the thickness of the component 2 are appropriately adapted to one
another.
The weld-in part 4 is automatically centred relative to the component 2 as
weld-in part 4 and component 2 are brought together because the thin disc
9A has a smaller diameter than the recess 3, and it is quite possible for
the thin disc 9A to come into contact with the wall of the recess 3, as
shown at point 12.
FIG. 11 shows the weld-in part 4 according to FIG. 10 together with the
component 2, more specifically as viewed from the side of the camber 10.
FIG. 11 shows the projection of the thin disc 9A, extending beyond the
edge 13, relative to the camber 10. FIG. 11 also shows the distance D from
the contact point 12. In this position of weld-in part 4 relative to
component 2, the distance D corresponds to about twice the difference in
the diameters of weld-in part 4 and recess 3.
FIG. 12 shows how the melting process initially takes place in the region
of the contact point 12 (see FIG. 10) after the arc has been switched on
(represented by the radiating lines 14). The thin disc 9A is reduced here
by melting until it passes into the region of the cone 8 and the camber
10, and as the distance between the remainder of the thin disc 9A and the
internal wall of the recess 3 increases, the arc is distributed, in
particular over the camber 10, which therefore melts and leads to a molten
pool on the bottom of the component 2 on the surface of the carrier 1,
into which pool the weld-in part 4 is finally immersed, the molten pool
extending over the entire camber 10, the opposing region of the carrier 1
and the internal wall of the recess 3. A secure weld between component 2
and carrier 1 is finally produced in this way by the molten material which
has melted from the thin disc 9A.
FIG. 13 shows a detail of a variation of the design of the weld-in part. In
this case, the weld-in part 4 passes via the cone 11 into a sharply
issuing cutting edge 15, the camber 10 facing the cone 11 on the other
side of the cutting edge 15. The cutting edge 15 projecting similarly to
the thin disc 9A of FIG. 10 ensures that rapid melting of the material of
the weld-in part 4 can take place in the region thereof. The action of the
weld-in part 4 shown in FIG. 13 is basically the same as that of the
weld-in part 4 according to FIG. 10.
A further design of the weld-in part 4 is shown in FIG. 14. In this case
the cone 8 of the weld-in part 4 runs onto a radial face 16 which is
limited outwardly by the edge 17 from which the camber 10 extends.
Depending on the height of the camber 10, a more or less thin cutting
edge-like rim with the relatively sharp edge 17 is therefore formed and
can be caused to melt in the manner described with reference to the
aforementioned embodiments.
Referring to the embodiment illustrated by FIGS. 5, 6 and 7, the weld-in
part 4 shown in FIG. 5 has shank 7 which is cylindrical in design. The
shank 7 passes via the cone 8 into the rim 9 which is also generally
cylindrical in shape. The convexly shaped camber 10 adjoins the rim 9.
Cone 8, rim 9 and camber 10 therefore form a head 11 of which the external
diameter produced by the rim 9 is greater than the diameter of the shank
7. The diameter of the head 11 is smaller than the opening of the recess 3
shown in FIG. 6. The cone 8 forms a step which can also be constructed as
a radial face. The bore 16 is provided in the weld-in part through shank 7
and extends into the head 11. The end wall 17A of the bore 16 has a
thickness corresponding approximately to the thickness of the wall 18 of
the shank 7.
FIG. 6 shows the weld-in part 4 according to FIG. 5 in section, more
specifically inserted into the recess 3 in the metal component 2. In the
simplest case, the recess 3 consists of a round bore. The metal component
2 lies directly on the carrier 1 consisting of a piece of sheet metal. The
metal component 2 is additionally pressed against the carrier 1 by the two
pressing members 19, 20.
According to FIG. 6, the conveyance and positioning of the weld-in part 4
is brought about by the setting tool 21 which engages bore 16 with its
expanding jaws 22, 23 during the expansion of which the weld-in part 4 is
kept tensioned from the interior. The expanding jaws are expanded by means
of the expansion mandrel 14 which, as with known expansion tools, urges
the expanding jaws 22 and 23 outwardly when driven in between the
expanding jaws 22 and 23. The setting tool 21 has a total of four
symmetrically-arranged expanding jaws, of which the illustrated expanding
jaws 22, 23 are separated from one another by the slot 25. The setting
tool 21 is designed as a welding tool, i.e. it is attached to a pole of a
voltage source for arc welding. The other pole is connected to the carrier
1. The weld-in part 4 and the carrier 1 therefore form the two electrodes
for arc welding, good contact with the weld-in part 4 being produced owing
to the easily produced considerable expanding force of the expanding jaws
22, 23.
The weld-in part 4 is pressed against the carrier 1 by the setting tool 21,
the voltage source for arc welding being attached to the weld-in part 4
and the carrier 1, as mentioned above. The welding arc is then struck in a
known manner, for which purpose the setting tool 21 is lifted from the
carrier 1 together with the weld-in part 4.
An arc is therefore struck between carrier 1 and the weld-in part 4,
leading to the formation of a pool of melt and eventually to the welding
of the respective parts, as already described hereinbefore.
The final welded joint is shown in a perspective view in FIG. 7. It shows
the carrier 1 with the component 2 from which the weld-in part 4 projects.
A bead 14 formed by the raised pool of melt extends around the weld-in
part 4, additionally embracing the weld-in part 4.
Owing to the bore 16 extending into the head 11, the weld-in part 4 forms a
hollow body with a wall having substantially the same thickness, in
particular in the region of the wall of the bore 16 and the end wall 17A
thereof. As a result, the weld-in part has a relatively low heat capacity,
that is to say can be heated suitably rapidly. During the cooling of the
weld-in part 4, this process also takes place without a particularly high
heat concentration as individual points of the weld-in part, producing a
substantially tension-free welding zone after cooling has taken place.
The carrier and the metal component can be metal sheets or the like. It is
also possible to design the metal component as a stronger constructional
element which then merely has to be provided with the above described
recess into which the head of the weld-in part has to penetrate. The
described arc welded joint is suitable, in particular, also for the
welding of aluminium parts with which welding is known to be difficult. In
particular, aluminium sheets can be joined to one another only with
difficulty by the known spot welding process as the oxide skin present on
the aluminium sheets has to be broken through. In addition, it should be
noted during spot welding that the electrodes placed onto the metal sheets
are contaminated relatively rapidly and therefore have to be cleaned
continually. With the arc welded joint according to the invention, on the
other hand, new electrodes are present continuously, namely in the form of
the carrier on the one hand and in the form of the weld-in part on the
other hand. As particularly high currents are required when welding
aluminium, the contact of the weld-in part via the internal wall of its
bore with the easily applied high contact pressures has a particularly
desirable effect.
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